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MB 351 - Host Defenses
Terms in this set (28)
What is normal flora and what does it do?
The normal flora are microbes in healthy plants and animals that usually protect their hosts. Prevent body from being colonized by other less benign symbionts.
How are animals characterized as healthy?
By near sterility of the deep tissue, heart, brain, liver, kidneys, muscles and bloodstream.
Which areas of the body are most colonized with microbes?
Mucous membranes of the head, genital tracts and the luminal space of the intestinal tract.
What are the barriers of host defense?
What are the flowing liquids of host defense?
What are the activities of host defenses?
bronchial cilia motion
What types of diseases and cancers can smoking cause?
Chronic obstructive pulmonary disease (COPD,
More frequent and severe lung infections
(especially secondary smoke and tuberculosis)
Coronary Heart Disease - possibly accelerating by
chronic lung infections-inflammation spreading
to the circulatory system.
Lung cancers - particularly large cell carcinomas.
Cancers of the mouth, gums, trachea, esophagus
(snuff and chew).
What is an opportunistic infection
Normal flora can cause disease when introduced
into internal areas of the body.
Other normal flora can become serious pathogens in their normal niche if conditions allow them to proliferate to a greater than normal `extent.
How can microbes reach the nutrients located in host cells?
Through tattooing and piercings, which lyse the host cells to release the nutrients.
What types of allergic reactions come from tattoos and piercings?
Tattoo dyes, particularly red dye, can cause allergic skin reactions, resulting in an itchy rash at the tattoo site.
This may occur when years after you get the tattoo.
Some piercing jewelry is made of nickel and brass - engender allergic reactions.
What are the blood-borne disease from tattoos and piercings?
If tattoo or piercing equipment -or tattoo dyes- are contaminated with infected blood a number of serious blood-borne diseases can be transmitted.
Hepatitis B & C and HIV, syphilis , tetanus and tuberculosis have been transmitted by tattoo.
Tattoo risk is serious enough the American Red Cross requires you to wait a year after getting a tattoo before donating blood.
What are the oral complications of jewelry?
Jewelry worn in tongue piercings can chip and
crack your teeth and cause gum damage
What are skin disorders associated with tattoos?
Your body may form bumps called granulomas
around tattoo ink, especially if your tattoo includes red ink.
Tattooing can also cause areas of raised, excessive scarring called keloids.
Keloids are more common in those with darker skin.
What are skin infections associated with tattoos?
Tattoos and piercings can lead to local bacterial infections.
Typical signs and symptoms of a skin infection include redness, warmth, swelling and a discharge containing pus.
What are skin infections associated with piercings?
Navel piercings take longer to heal — sometimes up to nine months — since
sweat under tight clothing will keep the area damp, increasing bacteria.
Infections from piercings in the upper ear cartilage are especially serious.
Since cartilage doesn't have its own blood supply taking antibiotics is often ineffective - the drug can't travel to the infection site.
Such infection can lead to cartilage damage and seriousresulting in permanent ear deformity.
What are the two, interlinked systems of host immunity?
Constitutive defenses called innate immunity:
- always activated
- activated by foreign motif molecules
Inducible defenses called adaptive immunity:
- specifically activated by foreign antigens
- creates immune memory for long term
What does innate immunity respond to and how fast?
Innate immunity rapidly responds to the
presence of foreign motif molecules
including; peptidoglycan, glycolipids, LPS,
lipoteichoic acid, lipoproteins, ssRNA,
flagellin, various bacterial membrane
What are the first cells that bind and respond to the foreign motif molecules?
Dendritic cells and leukocytes (white blood cells)
These cells are chemotactic and pursue gradients of motif molecules - eventually presenting them to the adaptive immune system.
What is phagocytosis and what are the two major types of phagocytic cells?
Phagocytosis is the engulfing and killing of invading microbes by immune cells.
Two major types of phagocytic cells include;
- Macrophages (Mφ) - a form of lymphocyte AND
- PolyMorphonuclear Neutrophils (PMNs),
also known as leukocytes, neutrophils or white blood cells
What are characteristics of PMNs?
PMNs are found mainly in blood;
They migrate from the blood to the site of active infection as a result of the inflammation process.
PMNs are short-lived and are continually replaced
- PMNs lack mitochondria
- PMNs use glycolysis pathways to generate ATP.
What are characteristics of macrophages?
Mφs (fixed and circulating) are found virtually everywhere within the body.
- Mφs are long-lived cells.
- Mφs have mitochondria.
- Mφs use respiratory (oxidative) pathways to generate ATP.
Both cell types move by amoeboid motion
- actively seeking out invading cellular microbes.
What do PMNs and Mφs have in common?
Both cell types engulf foreign bodies into an intracellular phagosome eventually fuses with a lysosome.
What occurs during phagolysosome?
a specialized killing sequence of reactions is initiated the oxidative burst
The phagocyte produces a series of toxic oxygen compounds designed to kill the phagocytosed prey.
- The oxidative burst requires aerobic conditions.
(Picture on slide)
What is the process of natural killer (NK) in destroying virus-infected host cells?
Virus-infected cells are recognized by
viral glycoprotein antigens on their surface.
When a natural killer (NK) cell encounters
a virus-infected target cells it binds tightly and destroys it.
- After binding, NK cells secrete perforin protein.
- Perforin dissolves into the target cell membrane forming a pore.
- After perforin, proteins called granzymes diffuse from the NK cell through the pore into the target cell.
- The granzymes initiate host cell apoptosis,
causing premature death of the target cell.
What are antimicrobial enzymes?
Lysozyme - found in saliva and tears
hydrolyzes peptidoglycan - work against Gram -positive bacteria
Phospholipase enzymes - secreted by skin cells
hydrolyze ester linkages in bacterial membranes
What are antimicrobial peptides?
Defensins and complement
What are defensins?
Defensins are peptides present on nearly all body surfaces and in all body tissues
Defensins are small, amphipathic protein molecules; 35-40 amino acids long, comprised of separate regions of polar and nonpolar amino acids
Humans have 2-14 copies of two different defensin genes.
Some defensins penetrate and aggregate
in bacterial membranes disrupting their integrity
What are complements?
Complement is the term for a group of 20+
antimicrobial proteins made in the liver.
Complement proteins enhance binding of phagocyte membranes to microbial surfaces
- The coating process called opsonization.